Photographic silver halide emulsions containing sydnones or sydnone imines as stabilizers

ABSTRACT

The photographic silver halide emulsion contains as a latentimage stabilizer the compound represented by the general formula   WHEREIN R1 represents a hydrogen atom, an allyl group, a heterocyclic ring, an unsubstituted or substituted lower alkyl group, an unsubstituted or substituted aryl group, or an unsubstituted or substituted lower aralkyl group; R2 represents a hydrogen atom, a halogen atom, an acetyl group, a carboxyl group, a formyl group, a nitro group, an amino group, or an unsubstituted or substituted carbamoyl group; X represents an oxygen atom or an unsubstituted or substituted imino group; and + OR - represents a resonance structure.

United States Patent [191 Noda et al.

[- May 6,1975

[ PHOTOGRAPHIC SILVER HALIDE EMULSIONS CONTAINING SYDNONES OR SYDNONE IMINES AS STABILIZERS [75] Inventors: Touru Noda; Norio Kobayashi, both of Kyoto, Japan [73] Assignee: Mitsubishi Paper Mills, Ltd., Tokyo,

Japan 22 Filed: May 17, 1973 211 Appl. No.: 361,086

[30] Foreign Application Priority Data May 17, 1972 Japan 47-48094 [52] US. Cl. 96/109 [51] Int. Cl G03c 1/34 [58] Field of Search 96/109, 33

[56] References Cited UNITED STATES PATENTS 3,422,759 1/1969 Brynko et a1. 96/33 3,589,898 6/l971 Fry et al. 96/33 Primary Examiner-David Klein Assistant ExaminerWon I-I. Louie, Jr.

Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT The photographic silver halide emulsion contains as a latent-image stabilizer the compound represented by the general formula R l 2 C 2 Claims, No Drawings PHOTOGRAPHIC SILVER I-IALIDE EMULSIONS CONTAINING SYDNONES OR SYDNONE IMINES AS STABILIZERS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a silver halide photographic emulsion and more particularly it relates to a photographic silver halide emulsion containing an improved latent-image stabilizer.

2, Description of the Prior Art It is well known that a latent image formed in photographic silver halide element by imagewise exposure cannot maintain its exposed state but varies with the passage of time. In negative photographic elements, the latent image formed grows or develops for a short period of time immediately after exposure, thereafter the latent image is maintained stably for a considerable period of time, and then fading begins. That is, negative silver halide photographic elements are usually accompanied by a so-called latent image fading phenomenon that when the silver halide photographic element is exposed and developed with some time interval after exposure, the density of the developed image is lower than that of the silver halide photographic element de veloped immediately after exposure.

The aforesaid phenomenon gives substantially no troubles in case of ordinary highsensitive negative photographic elements because in such a case the latent image formed is maintained stably for a considerably long period of time after exposure. On the other hand, in positive photographic elements, if some of gaslight papers or positive color photographic elements are allowed to stand for several tens hours after expo sure, the latent-image fading occurs strikingly, which results in causing insufficient printing. The problem of the occurence of latent-image fading becomes important recently even in positive color photographic elements in which the whiteness of blank is extremely required. This is because the latent-image fading frequently occurs strongly in positive color photographic elements, for example when a silver halide photographic emulsion having high sensitivity but gives less fogs is used for a positive color photographic element, the color photographic element frequently suffers from the occurence of strong latent-image fading and, when a ballasting coupler capable of forming a dye having excellent image stability is used, the latent-image fading is promoted by a high boiling oil which is a solvent for the coupler or is a dispersing agent for the coupler.

The stability of latent image is one of the most important practical characteristics of silver halide photographic elements and further is particularly important in multi-layer type color photographic elements. The color images having most desirable properties are obtained only when each emulsion layer of the multi-layer type color photographic element maintains the balance in respect of sensitivity and contrast and thus it is desirable that the latent-images formed by exposure be maintained stably without accompanied by fading during the preservation period before processing. If the latent-image in each emulsion layer does not vary with a same rate and in a same direction, the distortion of color balance will occur.

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is, therefore, to provide a silver halide photographic element having such a property that the change of latent image formed by exposure, in particular the tendency of causing latent fading during the preservation of the photographic element after exposure are greatly reduced.

In a photographic characteristic curve showing the relation betwen the density of image (D) and the lagarithm of exposure amount, the extent of the latentimage fading can be expressed by the ratio D/Do, wherein D0 is the density of the image obtained by de veloping directly after exposure at log E and D is the density of the image developed after fading, and as the value is smaller than 1, the extent of the latent-image fading is larger. That is, the object of this invention is to provide a silver halide photographic element having such a property that the value D/Do showing the fading ratio of the latentimage fading during the preservation of the silver halide photographic element after exposure.

Another object of this invention is to provide a silver halide photographic emulsion for the above-mentioned silver halide photographic element.

That latent-image fading becomes stronger as the preservation time of the silver halide element after exposure is longer and, in particular, it tends to occur faster and stronger under the conditions of high temperature and high humidity. Furthermore, the latentimage fading depends upon the wave length of light employed for the exposure. Still further, the speed and strength of latent-image fading deffer greatly according to the various properties of the silver halide photographic emulsion, such as the composition of silver halide, the grain size of silver halide, the crystallinity of silver halide, the silver ion density in the silver halide emulsion, the pH value of the emulsion, the kinds and amounts of gelatin and other binders if any, and the kinds of various additives contained in the silver halide emulsion. The causes of the above phenomena have not yet been cleared but the stability of the latentimage of a silver halide photographic element has an important meaning for the practical characteristics of the photographic element or is one of the important photographic characteristics of the silver halide photographic element and, in particular, the latent-image fading frequently depends upon various properties of silver halide emulsion. Thus, we have frequently experienced such an unpleasant fact that we tried to obtain silver halide photographic emulsions having high sensitivity but giving less fogs but the photographic emulsions obtained gave large latent-image fading after exposure.

Therefore, the inventors have made various investigations of obtaining silver halide photographic emulsions giving less latent-image fading during the preservation thereof after exposure and further giving less fogs and as the results thereof it has been discovered that the occurence of the latent-image fading of a silver halide photographic element is greatly reduced by incorporating in the silver halide photographic emulsion for the photographic element at least one compound represented by the general formula wherein R represents a hydrogen atom, an allyl group, a heterocyclic ring, an unsubstituted or substituted lower alkyl group, an unsubstituted or substituted aryl group, or an unsubstituted or substituted lower aralkyl group; R represents a hydrogen atom, a halogen atom, an acetyl group, a carboxyl group, a formyl group, a nitro group, an amino group, an unsubstituted or substituted lower alkyl group, an unsubstituted or substituted phenyl group, an unsubstituted or substituted carbamoyl group; X represents an oxygen atom or an unsubstituted or substituted imino group; and the sign i represents a resonance structure.

The present invention is based on the new discovery and according to the present invention, there is provided a silver halide photographic element which can maintain the latent image formed therein by exposure stably without causing latent-image fading and causes no insufficient density and the distortion of color balance when the photographic silver halide element is preserved after exposure.

The compound represented by the aforesaid general formula I is a compound called sydnone and sydnoneimine and practical examples of the compound are shown below by way of only illustration.

That is, they are 3allylsydonone, 3- furfurylsydonone, 3-(3-pyridyl)sydonone, hexadecylsydonone, 3-[3-(dimethylamino)-propyl]sydonone, 3- phenylsydonone, 3 ,4-diphenylsydonone, 3-( 2- naphthyl)sydonone, 4-bromo-3-(p-ethoxyphenyl)sydonone, 4-methyl-3-(2,6-xylyl) sydonone, 3-(m-methoxybenzyl)sydonone, 4-formyl-3-phenylsydonone, 4-acetyl-3-phenylsydonone, 4-nitro-3-o-tolylsydonone, 4-carb0xysydonone, 3-butyl-4-carbamoylsydonone, 4- cyclohexylcarbamoyl )-3-phenylsydonone, 4-( 2 ,4- dinitrophenyl)-3-methylsydonone, 4-amino-3- phenylsydonone, 4(phenylhydroxymethyl )-3- phenylsydonone, 3-phenylsydonone-4-carboxylic acid, 4-( p-chlorophenyl)-3-p-tolylsydononeimine, 3-( 2- chloroethyl)sydononeimine, N-acetyl-3- benzylsydononeimine, N-benzoyl-4-bromo-3- isobutylsydononeimine, N-carboxyl3-p tolysydononeimine. 3-octyl-N-(phenylcarbamoyl)- mentioned above.

Also, the silver halide emulsion of this invention may contain various other additives such as a chemical sensitizer (e.g., a sulfur sensitizer, various kinds of metal sensitizers, primary to ternary amine, quaternary ammonium salt, etc.,), a spectral sensitizer, a super dye sensitizer, an antifoggant, a stabilizer, a surface active agent, a development accelrator, a bleaching accelerator, a hardening agent, a coupler for forming colored dye, and a solvent and dispersing agent for the coupler.

The amount of the sydonone or the sydononeimine having the aforesaid general formula 1 to be incorporated in silver halide photographic emulsion of this invention depends upon the nature of the silver halide emulsion, the kinds of various additives to be incorporated in the silver halide emulsion, the kind of the compound having the formula I, and the condition for desired latent-image stability but in general the amount is in a range of 0.1-2 g per mol of the silver halide contained in the silver halide emulsion.

The optimum amount of the compound can be easily determined by a method known in the field of art. For example, a silver halide photographic emulsion is divided into plural portions, the compound having the formula I is incorporated in each of the divided photographic emulsions in different amount, each sample of the silver halide emulsion containing the compound is applied to a base support to form the emulsion layer, and then each of the emulsion layers thus formed is exposed. Then, one of the exposed sample is developed immediately after exposure, while other one of them is exposed after preserving for a definite period of time at a constant temperature. By this method the effect of the above-mentioned compound to the occurence of latent-image fading can be easily determined.

The silver halide photographic emulsion of this invention may be applied to any supports ordinary employed for the purpose, such as papers, acetyl cellulose films, nitrocellulose films, other synthetic resin films, laminate papers prepared by laminating a synthetic resin on papers.

Then, the invention is explained more practically in the following examples:

EXAMPLE 1 To a bluesensitive silver halide photographic emulsion 10 g. of silver nitrate) having silver halide composition of AgBr/AgCl/Agl /7/3 prepared by an ammonia method was added 4 ml. of 0.1% aqueous hypo solution and after adjusting the pH of the silver halide emulsion to 6.0 by a pH adjusting agent, the silver halide emulsion was subjected to a secondary ripening for 40 minutes at 55C. After ripening, a stabilizer, an antifoggant, and the compound in this invention, 3- phenylsydonone were added to the emulsion as, preferably, l% methanol solution. Apart from this, 20 ml. of 5% aqueous sodium dodecylbenzensulfonate solution was added to ml. of 10% aqueous gelatin solution and then a solution of 10 g. of the coupler shown by the formula II Coupler ll Nil-CO (CH2)3O in a mixture of 60 ml. of ethyl acetate and 5 ml. of dibutyl phthalate was dispersed in the gelatin solution prepared above followed by removing ethyl acetate. The dispersion thus prepared was added to the aforesaid blue-sensitive silver halide photographic emulsion. After adding further to the mixture a hardening agent, a development accelerator, and a bleaching accelerator and then adjusting the pH of the emulsion by a pH adjusting agent to 6.5, water was added thereto to make 560 g. of the total amount. The silver halide emulsion thus prepared was applied in layers to a photographic baryta-coated paper in a coating amount of 70 g./m together with the following protective layer for the blue-sensitive emulsion layer.

That is, g. of was dissolved in 400 g. of water and after adding thereto a hardening agent and a surface active agent, water was added to make 540 g. of the total amount. The gelatin solution was applied to the blue-sensitive silver halide emulsion layer as the protective layer in a coating amount of 60 g/m The sample was then dried, cut, and exposed. One of the exposed sample was immediately developed and one of them was developed after preserving for 4 days at temperature of 35C. and at humidity of 80%.

The processing used above was as follows:

Color development (6 minutes, developer CD-lll, trade name of Eastman Kodak Co.) stopfixing (2 minutes) first washing (2 minutes) ferricyanide bleaching (2 minutes) second washing (2 minutes)- hardening fixing (4 minutes) third washing (4 minutes) stabilization (2 minutes).

The results obtained about the cases of adding 3- phenyl-sydonone in several different amounts are shown in the following table together with the results of the case adding no compound of this invention to the blue-sensitive emulsion layer. In addition, the latent-.

(A) (B) Latent-image fading ratio Note;

(A) Amount (mg) of the compound added to the emulsion per 10 g. of silver nitrate.

(B) Relative sensitivity processed immediately after exposure.

As clear from the table, it will be understood well that the latent-image fading could be remarkably prevented by the addition of the compound in this invention, 3-phenylsydonone.

EXAMPLE 2 The same procedure as in Example 1 was followed using various compounds in this invention instead of 3-pheny1sydonone, the results being shown in the following table.

Note:

(A), (B). and the latent-image fading ratios are same as in the table in Example 1.

As clear from the above table, it will be understood well that the latent-image fadling could be prevented remarkably by the addition of the compounds in this invention.

EXAMPLE 3 The pH of a green-sensitive silver halide emulsion (5.3 g. of silver nitrate) having a silver halide composition of AgBr/AgCl /40 prepared by an acid method was adjusted to 5.9 by a pH adjusting agent and then the emulsion was subjected to secondary ripening for 45 minutes at 50C. After ripening, 2.5 ml. of 1% methanol solution of a stabilizer, an antifoggant, and the compound of this invention, 3,4-diphenylsydonone was added to the emulsion. Apart from this, 10 m1. of 5% aqueous sodium dodecylbenzemesulfonate solution was added to 50 ml. of 10% aqueous gelatin solution and a solution of 3 g. of the magenta coupler I11 in a mixture of 40 ml. of ethyl acetate and 25 ml. of dibutyl phthalate was dispersed in the above gelatin solu tion. Then, after removing ethyl acetate, the dispersion was added to the green-sensitive photographic emulsion. After adding further to the silver halide emulsion a sensitizing dye and a hardening agent and adjusting the pH of the emulsion to 6.5 by a pH adjusting agent, the total amount of the emulsion was adjusted to 420 g. by water and then the resultant emulsion was applied to a baryta-coated paper in a coating amount of 60 g./m together with a protective layer having the same composition as in Example 1.

The results obtained by processing as in Example 1 are shown in the following table together with the results obtained by processing in the case of containing no compound of this invention. The results in the table were calculated based on the density of the magenta image after color development and bleach.

As clear from the table, it will be understood well that the compound of this invention could prevent greatly the occurence of the latent-image fading even in the silver halide emulsion different from those of Example 1.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

l. A photographic silver halide emulsion containing in an amount of 0.1 to 2 g. per mol of the silver halide in the emulsion at least one compound represented by the formula wherein R represents a hydrogen atom, an allyl group, a heterocyclic ring, an unsubstituted alkyl group or an alkyl group substituted with a halogen atom or a alkylamino group, an unsubstituted aryl group or an aryl group substituted with an alkyl or an alkoxy, or an unsubstituted aralkyl group or an aralkyl group substituted with an alkoxy group; R represents a hydrogen atom, a halogen atom, an amino group, a carboxyl group, a formyl group, a nitro group, an acetyl group, an unsubstituted carbamoyl group or a carbamoyl substituted with a cycloalkyl or a phenyl group, a lower alkyl group or a lower alkyl group substituted with a phenyl or a hydroxyl group, or an unsubstituted phenyl group or a phenyl group substituted with a halogen atom or a nitro group and X represents an oxygen atom, or an unsubstituted imino group or an imino group substituted with an acyl, a carboxyl or a carbamoyl group; and the sign i represents a resonance structure.

2. A photographic silver halide element comprising a support bearing thereon a silver halide emulsion layer containing in an amount of 0.1 to 2 g. per mol of the silver halide in the emulsion the compound represented by the formula wherein R represents a hydrogen atom, an allyl group, a heterocyclic ring, an unsubstituted alkyl group or an alkyl group substituted with a halogen atom or a alkylamino group, an unsubstituted aryl group or an aryl group substituted with an alkyl or an alkoxy, or an unsubstituted aralkyl group or an aralkyl group substituted with an alkoxy group; R represents a hydrogen atom, a halogen atom, an amino group, a carboxyl group, a formyl group, a nitro group, an acetyl group, an unsubstituted carbamoyl group or a carbamoyl substituted with a cycloalkyl or a phenyl group, a lower alkyl group or a lower alkyl group substituted with a phenyl or a hydroxyl group, or an unsubstituted phenyl group or a phenyl group substituted with a halogen atom or a nitro group; and X represents an oxygen atom, or an unsubstituted imino group or an imino group substituted with an acyl, a carboxyl or a carbamoyl group; and the sign i represents a resonance structure. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING IN AN AMOUNT OF 0.1 TO 2 G. PER MOL OF THE SILVER HALIDE IN THE EMULSSION AT LEAST ONE COMPOUND REPRESENTED BY THE FORMULA
 2. A photographic silver halide element comprising a support bearing thereon a silver halide emulsion layer containing in an amount of 0.1 to 2 g. per mol of the silver halide in the emulsion the compound represented by the formula 